[NETFILTER]: Convert DEBUGP to pr_debug
[linux-2.6.git] / net / netfilter / nf_conntrack_proto_gre.c
1 /*
2  * ip_conntrack_proto_gre.c - Version 3.0
3  *
4  * Connection tracking protocol helper module for GRE.
5  *
6  * GRE is a generic encapsulation protocol, which is generally not very
7  * suited for NAT, as it has no protocol-specific part as port numbers.
8  *
9  * It has an optional key field, which may help us distinguishing two
10  * connections between the same two hosts.
11  *
12  * GRE is defined in RFC 1701 and RFC 1702, as well as RFC 2784
13  *
14  * PPTP is built on top of a modified version of GRE, and has a mandatory
15  * field called "CallID", which serves us for the same purpose as the key
16  * field in plain GRE.
17  *
18  * Documentation about PPTP can be found in RFC 2637
19  *
20  * (C) 2000-2005 by Harald Welte <laforge@gnumonks.org>
21  *
22  * Development of this code funded by Astaro AG (http://www.astaro.com/)
23  *
24  */
25
26 #include <linux/module.h>
27 #include <linux/types.h>
28 #include <linux/timer.h>
29 #include <linux/list.h>
30 #include <linux/seq_file.h>
31 #include <linux/in.h>
32 #include <linux/skbuff.h>
33
34 #include <net/netfilter/nf_conntrack_l4proto.h>
35 #include <net/netfilter/nf_conntrack_helper.h>
36 #include <net/netfilter/nf_conntrack_core.h>
37 #include <linux/netfilter/nf_conntrack_proto_gre.h>
38 #include <linux/netfilter/nf_conntrack_pptp.h>
39
40 #define GRE_TIMEOUT             (30 * HZ)
41 #define GRE_STREAM_TIMEOUT      (180 * HZ)
42
43 static DEFINE_RWLOCK(nf_ct_gre_lock);
44 static LIST_HEAD(gre_keymap_list);
45
46 void nf_ct_gre_keymap_flush(void)
47 {
48         struct list_head *pos, *n;
49
50         write_lock_bh(&nf_ct_gre_lock);
51         list_for_each_safe(pos, n, &gre_keymap_list) {
52                 list_del(pos);
53                 kfree(pos);
54         }
55         write_unlock_bh(&nf_ct_gre_lock);
56 }
57 EXPORT_SYMBOL(nf_ct_gre_keymap_flush);
58
59 static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
60                                 const struct nf_conntrack_tuple *t)
61 {
62         return km->tuple.src.l3num == t->src.l3num &&
63                !memcmp(&km->tuple.src.u3, &t->src.u3, sizeof(t->src.u3)) &&
64                !memcmp(&km->tuple.dst.u3, &t->dst.u3, sizeof(t->dst.u3)) &&
65                km->tuple.dst.protonum == t->dst.protonum &&
66                km->tuple.dst.u.all == t->dst.u.all;
67 }
68
69 /* look up the source key for a given tuple */
70 static __be16 gre_keymap_lookup(struct nf_conntrack_tuple *t)
71 {
72         struct nf_ct_gre_keymap *km;
73         __be16 key = 0;
74
75         read_lock_bh(&nf_ct_gre_lock);
76         list_for_each_entry(km, &gre_keymap_list, list) {
77                 if (gre_key_cmpfn(km, t)) {
78                         key = km->tuple.src.u.gre.key;
79                         break;
80                 }
81         }
82         read_unlock_bh(&nf_ct_gre_lock);
83
84         pr_debug("lookup src key 0x%x for ", key);
85         NF_CT_DUMP_TUPLE(t);
86
87         return key;
88 }
89
90 /* add a single keymap entry, associate with specified master ct */
91 int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
92                          struct nf_conntrack_tuple *t)
93 {
94         struct nf_conn_help *help = nfct_help(ct);
95         struct nf_ct_gre_keymap **kmp, *km;
96
97         kmp = &help->help.ct_pptp_info.keymap[dir];
98         if (*kmp) {
99                 /* check whether it's a retransmission */
100                 list_for_each_entry(km, &gre_keymap_list, list) {
101                         if (gre_key_cmpfn(km, t) && km == *kmp)
102                                 return 0;
103                 }
104                 pr_debug("trying to override keymap_%s for ct %p\n",
105                          dir == IP_CT_DIR_REPLY ? "reply" : "orig", ct);
106                 return -EEXIST;
107         }
108
109         km = kmalloc(sizeof(*km), GFP_ATOMIC);
110         if (!km)
111                 return -ENOMEM;
112         memcpy(&km->tuple, t, sizeof(*t));
113         *kmp = km;
114
115         pr_debug("adding new entry %p: ", km);
116         NF_CT_DUMP_TUPLE(&km->tuple);
117
118         write_lock_bh(&nf_ct_gre_lock);
119         list_add_tail(&km->list, &gre_keymap_list);
120         write_unlock_bh(&nf_ct_gre_lock);
121
122         return 0;
123 }
124 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_add);
125
126 /* destroy the keymap entries associated with specified master ct */
127 void nf_ct_gre_keymap_destroy(struct nf_conn *ct)
128 {
129         struct nf_conn_help *help = nfct_help(ct);
130         enum ip_conntrack_dir dir;
131
132         pr_debug("entering for ct %p\n", ct);
133
134         write_lock_bh(&nf_ct_gre_lock);
135         for (dir = IP_CT_DIR_ORIGINAL; dir < IP_CT_DIR_MAX; dir++) {
136                 if (help->help.ct_pptp_info.keymap[dir]) {
137                         pr_debug("removing %p from list\n",
138                                  help->help.ct_pptp_info.keymap[dir]);
139                         list_del(&help->help.ct_pptp_info.keymap[dir]->list);
140                         kfree(help->help.ct_pptp_info.keymap[dir]);
141                         help->help.ct_pptp_info.keymap[dir] = NULL;
142                 }
143         }
144         write_unlock_bh(&nf_ct_gre_lock);
145 }
146 EXPORT_SYMBOL_GPL(nf_ct_gre_keymap_destroy);
147
148 /* PUBLIC CONNTRACK PROTO HELPER FUNCTIONS */
149
150 /* invert gre part of tuple */
151 static int gre_invert_tuple(struct nf_conntrack_tuple *tuple,
152                             const struct nf_conntrack_tuple *orig)
153 {
154         tuple->dst.u.gre.key = orig->src.u.gre.key;
155         tuple->src.u.gre.key = orig->dst.u.gre.key;
156         return 1;
157 }
158
159 /* gre hdr info to tuple */
160 static int gre_pkt_to_tuple(const struct sk_buff *skb,
161                            unsigned int dataoff,
162                            struct nf_conntrack_tuple *tuple)
163 {
164         struct gre_hdr_pptp _pgrehdr, *pgrehdr;
165         __be16 srckey;
166         struct gre_hdr _grehdr, *grehdr;
167
168         /* first only delinearize old RFC1701 GRE header */
169         grehdr = skb_header_pointer(skb, dataoff, sizeof(_grehdr), &_grehdr);
170         if (!grehdr || grehdr->version != GRE_VERSION_PPTP) {
171                 /* try to behave like "nf_conntrack_proto_generic" */
172                 tuple->src.u.all = 0;
173                 tuple->dst.u.all = 0;
174                 return 1;
175         }
176
177         /* PPTP header is variable length, only need up to the call_id field */
178         pgrehdr = skb_header_pointer(skb, dataoff, 8, &_pgrehdr);
179         if (!pgrehdr)
180                 return 1;
181
182         if (ntohs(grehdr->protocol) != GRE_PROTOCOL_PPTP) {
183                 pr_debug("GRE_VERSION_PPTP but unknown proto\n");
184                 return 0;
185         }
186
187         tuple->dst.u.gre.key = pgrehdr->call_id;
188         srckey = gre_keymap_lookup(tuple);
189         tuple->src.u.gre.key = srckey;
190
191         return 1;
192 }
193
194 /* print gre part of tuple */
195 static int gre_print_tuple(struct seq_file *s,
196                            const struct nf_conntrack_tuple *tuple)
197 {
198         return seq_printf(s, "srckey=0x%x dstkey=0x%x ",
199                           ntohs(tuple->src.u.gre.key),
200                           ntohs(tuple->dst.u.gre.key));
201 }
202
203 /* print private data for conntrack */
204 static int gre_print_conntrack(struct seq_file *s,
205                                const struct nf_conn *ct)
206 {
207         return seq_printf(s, "timeout=%u, stream_timeout=%u ",
208                           (ct->proto.gre.timeout / HZ),
209                           (ct->proto.gre.stream_timeout / HZ));
210 }
211
212 /* Returns verdict for packet, and may modify conntrack */
213 static int gre_packet(struct nf_conn *ct,
214                       const struct sk_buff *skb,
215                       unsigned int dataoff,
216                       enum ip_conntrack_info ctinfo,
217                       int pf,
218                       unsigned int hooknum)
219 {
220         /* If we've seen traffic both ways, this is a GRE connection.
221          * Extend timeout. */
222         if (ct->status & IPS_SEEN_REPLY) {
223                 nf_ct_refresh_acct(ct, ctinfo, skb,
224                                    ct->proto.gre.stream_timeout);
225                 /* Also, more likely to be important, and not a probe. */
226                 set_bit(IPS_ASSURED_BIT, &ct->status);
227                 nf_conntrack_event_cache(IPCT_STATUS, skb);
228         } else
229                 nf_ct_refresh_acct(ct, ctinfo, skb,
230                                    ct->proto.gre.timeout);
231
232         return NF_ACCEPT;
233 }
234
235 /* Called when a new connection for this protocol found. */
236 static int gre_new(struct nf_conn *ct, const struct sk_buff *skb,
237                    unsigned int dataoff)
238 {
239         pr_debug(": ");
240         NF_CT_DUMP_TUPLE(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple);
241
242         /* initialize to sane value.  Ideally a conntrack helper
243          * (e.g. in case of pptp) is increasing them */
244         ct->proto.gre.stream_timeout = GRE_STREAM_TIMEOUT;
245         ct->proto.gre.timeout = GRE_TIMEOUT;
246
247         return 1;
248 }
249
250 /* Called when a conntrack entry has already been removed from the hashes
251  * and is about to be deleted from memory */
252 static void gre_destroy(struct nf_conn *ct)
253 {
254         struct nf_conn *master = ct->master;
255         pr_debug(" entering\n");
256
257         if (!master)
258                 pr_debug("no master !?!\n");
259         else
260                 nf_ct_gre_keymap_destroy(master);
261 }
262
263 /* protocol helper struct */
264 static struct nf_conntrack_l4proto nf_conntrack_l4proto_gre4 = {
265         .l3proto         = AF_INET,
266         .l4proto         = IPPROTO_GRE,
267         .name            = "gre",
268         .pkt_to_tuple    = gre_pkt_to_tuple,
269         .invert_tuple    = gre_invert_tuple,
270         .print_tuple     = gre_print_tuple,
271         .print_conntrack = gre_print_conntrack,
272         .packet          = gre_packet,
273         .new             = gre_new,
274         .destroy         = gre_destroy,
275         .me              = THIS_MODULE,
276 #if defined(CONFIG_NF_CT_NETLINK) || defined(CONFIG_NF_CT_NETLINK_MODULE)
277         .tuple_to_nfattr = nf_ct_port_tuple_to_nfattr,
278         .nfattr_to_tuple = nf_ct_port_nfattr_to_tuple,
279 #endif
280 };
281
282 static int __init nf_ct_proto_gre_init(void)
283 {
284         return nf_conntrack_l4proto_register(&nf_conntrack_l4proto_gre4);
285 }
286
287 static void nf_ct_proto_gre_fini(void)
288 {
289         nf_conntrack_l4proto_unregister(&nf_conntrack_l4proto_gre4);
290         nf_ct_gre_keymap_flush();
291 }
292
293 module_init(nf_ct_proto_gre_init);
294 module_exit(nf_ct_proto_gre_fini);
295
296 MODULE_LICENSE("GPL");